1. Field of the Invention
The present invention relates to telecommunications systems and methods and more specifically to a high-quality voice network architecture over IP Centrex.
2. Introduction
The present invention relates to how one manages a telephone service. There are a group of well-known telephone service providers and technologies such as the legacy public switched telephone network (PSTN). Newer technologies are enabling telephone service via other networks such as the Internet, packet-switched or wireless networks. One such network is referred to as a “Centrex” solution. The term Centrex relates to a set of business solutions for voice services primarily where the equipment providing call control and service control operations is owned and operated by a service provider and is therefore typically located on a service provider's premises. There are advances to this arrangement. Centrex frees a customer from costs and responsibilities of owning equipment and it can be thought of as an outsourcing solution.
There are basic functions associated with call control and service logic in maintaining a telephone network. The following functions are examples of such services: recognizing that a party is “off hook” and that a dial tone should be provided, interpreting the dialed digits to determine where the call is to terminate, determining whether a party is available, busy, or has call forwarding, applying a busy signal, applying a call waiting tone, delivering a call to voicemail, recognizing when the called party answers the phone and when either party subsequently hangs up, and so forth.
In a traditional Centrex service, such as an analog or IDSN Centrex service, call control and call service logic reside in a class 5 switch located in a central office. A class 5 switch is responsible for transporting and switching the electrical signals that carry the caller's speech or other information.
As mentioned above, packet networks such as the Internet or other IP protocol networks are being used now for voice transmission. These services are often referred to as “IP Telephony”. In IP telephony, voice conversations can be digitized and packetized for transmission across the network. The term “IP Centrex” refers to a number of IP telephony solutions where Centrex service is offered to a customer who transmits its voice calls to the network as packetized streams across a broadband access facility. IP Centrex builds on the traditional benefits of Centrex by combining them with the benefits of IP telephony.
One of these IP telephony benefits is increased utilization of access capacity. In IP Centrex, a single broadband access facility is used to carry the packetized voice streams for many simultaneous calls. When calls are not active, more bandwidth is available for high speed data sessions over the LAN, like Internet access. This is a much more efficient use of capacity than traditional Centrex. In analog Centrex, one pair of copper wires is need to serve each analog telephone station, regardless of whether the phone has an active call; one the phone is not engaged in a call, the bandwidth capacity of those wires is unused. An ISDN BRI can support two simultaneous calls (i.e., 128 kbps), but similar to analog lines, an idle BRI's bandwidth capacity cannot be used to increase the corporate LAN's interconnection speed.
In IP Centrex, one customer premises equipment (CPE) communications via the network with another customer premises equipment (CPE) according to typically 4 digit dialing plans. For example, one person within a company may be calling another person within the company using a 4 digit number. Within the CPE-to-CPE context, the network or the class 5 switch typically negotiates a bandwidth of 64 kbps and then goes down depending on the particular compression scheme utilized. The problem with this approach is that the resulting negotiated bandwidth may not provide for a quality voice signal for the communication between users. Thus, although the IP Centrex system is used, the ultimate voice conversation is not achieved with as high a quality as would be desired. The CPE may be any phone or computing device such as a desktop computer that can operate to enable a user to initiate a call to the network and that can perform the steps of the invention.
The reduction in sound quality over the telephone has many downsides. For example, in normal conversation, sounds or portions of words spoken may be dropped or lost via the low bandwidth. These kinds of disturbances hinder the enjoyment of any conversation. In many languages, small sound nuances provide different meanings and any degree of reduced sound quality reduces the capability of hearing and understanding the speaker.
In addition to human-human interaction, the instances of human-computer speech interaction are also increasing. For example, people may call a help line for a business and engage in a human-computer dialog using technology available from AT&T Corp. These speech services include a speech server that includes modules for automatic speech recognition (ASR), language understanding, dialog analysis, and text-to-speech for carrying on a conversation with the user using natural language. These components are known to those of skill in the art. These systems, however, require clean speech from the user to provide accurate and acceptable ASR. With standard telephone speech, however, the low-bandwidth speech, with dropped portions of words transmitted and low quality sound “hear” by the ASR module of a speech recognition system, reduce the capability of the system to engage the user in a normal conversation.
What is needed in the art is an efficient and effective technology for improving the quality of voice and other sounds transmitted over a Centrex based network.